The long-term objective of this proposal is to explore immunization routes and antigen forms to induce immune responses in the human female genital tract. Statistical data indicate that more than 70% of infections with HIV are acquired by heterosexual transmission through the mucosal surfaces of the genital tract. Because conventional systemic immunization is usually ineffective to induce a specific immune response in external secretions, novel immunization routes and strategies have to be developed have to be developed to generate mucosal antibodies that would protect against HIV infection at the most frequent site of entry. Therefore, the purpose of the proposed studies is to determine the origin and properties of specific antibodies in human female genital secretions,m the origin of antibody-secreting plasma cells in genital tissues, and immunization protocols that result in the selective appearance of specific antibodies in female genital secretions. In the selection of suitable antigens for human administration, live and inactivated commercially available poliovirus vaccine and live Salmonella typhi Ty21a vaccine were considered as prototype antigens, that are relevant to the vaccine delivery systems proposed in component projects I and II (recombinant Salmonella and poliovirus-based vector systems). Single and repeated systemic, oral, rectal, and vaginal immunizations (and combinations of these routes) will be performed. The influence of antigen form (inactivated v live) on the ensuing responses, and the humoral immune responses induced by various immunization routes, will be evaluated with respect to: a) the isotype and subclass of antigen-specific serum and mucosal antibodies; b) molecular properties of IgA, including polymeric/monomeric forms and association with secretory component (SC) and J chain, constituting secretory IgA (S-IgA) molecule; c) duration of the immune response after single and repeated immunizations by systemic or mucosal routes; and d) the isotype(s) and frequency of antigen-specific and total antibody- secreting cells (AbSC) in peripheral blood and in dissociated uterine cervix (from women immunized before hysterectomy) as assessed by the ELISPOT technique. The accumulated information will provide a rational basis for effective and practical immunization strategies that generate mucosal immunity against genitally acquired AIDS and sexually transmitted diseases.